Always loved 12" figures. They are huge and a lot of fun to play with. We got a very cool Ultimate Powers Superman 12" figure at the flea market last weekend. It features three different play modes, makes sounds (he actually says phrases from the Superman Returns film) and lights itself. It is nicely sculpted, and the punch feature is a neat idea.
Like all the boys of his age, my son loves Spider-Man. We already owned most of the villains of the Spider-Man universe but one we were missing was Hobgoblin. Standing at 6" tall, this is a very cool figures with lots of details, articulated parts and it actually look somewhat menacing!